Intelligent Transport Systems (ITS); Cooperative ITS (C-ITS); Release 1 Vehicular Communications - GeoNetworking - Part 3 Network Architecture

8/12/2019 Intelligent Transport Systems (ITS); Cooperative ITS (C-ITS); Release 1 Vehicular Communications - GeoNetworking

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ETSI TS 102 636-3 V1.1.1 (2010-03)Technical Specification

Intelligent Transport Systems (ITS);Vehicular Communications;

GeoNetworking;Part 3: Network architecture


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ReferenceDTS/ITS-0030004

Keywords

addressing, ITS, network, point-to-multipoint,point-to-point, protocol

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Contents

Intellectual Property Rights ................................................................................................................................ 4

Foreword ............................................................................................................................................................. 4

Introduction ........................................................................................................................................................ 4

1 Scope ........................................................................................................................................................ 5

2 References ................................................................................................................................................ 52.1 Normative references .......................................................... ............................................................ ................... 5

2.2 Informative references ............................................................. ........................................................ ................... 6

3 Definitions and abbreviations ................................................................................................................... 63.1 Definitions ............................................................... .............................................................. ............................. 6

3.2 Abbreviations ................................................................ ........................................................ ............................. 7

4 Network architecture for ITS stations ...................................................................................................... 8

5 Deployment scenarios of the generic network architecture.................................................................... 10

6 Components of the network architecture ................................................................................................ 116.1 General ................................................... ............................................................ .............................................. 11

6.2 Sub-components of vehicle ITS stations and roadside ITS stations .......................................................... ....... 12

6.3 Network connectivity among ITS stations ........................................................ ............................................... 13

6.4 Network reference points ....................................................... ....................................................... ................... 14

7 ITS station protocol architecture ............................................................................................................ 157.1 Protocol stack overview ...................................................... ........................................................... .................. 15

7.2 Protocols of the ITS network & transport layer .................................................... ............................................ 16

7.3 Assembly of network and transport protocols in the ITS station protocol stack .............................................. 17

7.3.1 Overview ....................................................... ......................................................... .................................... 17

7.3.2 GeoNetworking protocol stack .................................................... ....................................................... ........ 177.3.3 IPv6 stack ..................................................... ........................................................ ...................................... 17

7.3.4 Combination of the GeoNetworking protocol and IPv6 ................................................. ............................ 18

7.3.5 Protocol stacks for other network protocols ................................................... ............................................ 18

8 Interfaces and service access points ....................................................................................................... 18

9 Frameworks for network and transport protocols .................................................................................. 209.1 GeoNetworking ................................................ ........................................................ ........................................ 21

9.1.1 Ad hoc networking..................................................................... ......................................................... ........ 21

9.1.2 Addressing .................................................. ........................................................ ........................................ 21

9.1.3 Resource management and data congestion control ................................................ ................................... 21

9.1.4 Integration of GeoNetworking and IPv6 .................................................... ................................................. 21

9.1.5 Backward compatibility to IPv4 ......................................................... ........................................................ 21

9.1.6 Usage of multiple ITS access technologies ........................................................... ...................................... 22

9.1.7 Security and privacy protection ............................................................ ...................................................... 22

9.2 Other protocol stacks ................................................... ......................................................... ............................ 22

History .............................................................................................................................................................. 23


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Intellectual Property Rights

IPRs essential or potentially essential to the present document may have been declared to ETSI. The information

pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found

in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI inrespect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web

server (http://webapp.etsi.org/IPR/home.asp).

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guaranteecan be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web

server) which are, or may be, or may become, essential to the present document.

Foreword

This Technical Specification (TS) has been produced by ETSI Technical Committee Intelligent Transport System (ITS).

The present document is part 3 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.13].

Introduction

The present document specifies the network architecture for communication-based Intelligent Transport Systems (ITS)

using different ITS access technologies, such as ITS-G5. The network architecture provides - in combination with the

description of scenarios - a basis for the technical specification of the network and transport protocols, in particular for

GeoNetworking and its related protocols.

The present document first introduces a generic, high-level system view of the network architecture and defines four

basic deployment scenarios. Based on the system view, it identifies and describes the main network components andspecifies network reference points among them. Central component of the architecture is the ITS station. For this

component, an overview of its protocol architecture is given and different options of using the GeoNetworking protocol

in combination with transport protocols and protocols of the IP suite are described. Finally, the present document

defines frameworks for different aspects of networking and data transport, such as ad hoc communication, addressing,

resource management and data congestion control, integration with protocols of the IP suite and others.

The network architecture is based on the ITS architecture specified in [1] and represents the networking viewpoint of

the overall architecture.

Sources of input for the present document are [i.1], [i.2] and [i.3].
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1 Scope

The present document specifies the network architecture for communication-based Intelligent Transport Systems (ITS).

The network architecture is focused on, but not limited to, vehicular communication. The architecture enables a wide

range of ITS applications for road safety, traffic efficiency as well as for infotainment and business.

The present document defines the framework for network and data transport protocols that provide data exchange

among ITS stations. A particular aspect is the GeoNetworking protocol that provides ad hoc and multi-hop

communication over short-range wireless technologies utilizing geographical positions.

2 References

References are either specific (identified by date of publication and/or edition number or version number) or

non-specific.

For a specific reference, subsequent revisions do not apply.

Non-specific referencemay be made only to a complete document or a part thereof and only in the followingcases:

- if it is accepted that it will be possible to use all future changes of the referenced document for thepurposes of the referring document;

- for informative references.

Referenced documents which are not found to be publicly available in the expected location might be found at

http://docbox.etsi.org/Reference.

NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guaranteetheir long term validity.

2.1 Normative references

The following referenced documents are indispensable for the application of the present document. For datedreferences, only the edition cited applies. For non-specific references, the latest edition of the referenced document

(including any amendments) applies.

[1] ETSI EN 302 665: "Intelligent Transport Systems (ITS); Communications Architecture".

[2] ISO/IEC 7498-1: "Information technology - Open Systems Interconnection - Basic Reference

Model: The Basic Model".

[3] ISO/IEC 8802-2: " Information technology - Telecommunications and information exchangebetween systems - Local and metropolitan area networks - Specific requirements; Part 2: Logical

Link Control".

[4] IETF RFC 791: "Internet Protocol".

[5] IETF RFC 2460: "Internet Protocol, Version 6 (IPv6) Specification".

[6] IETF RFC 3775: "Mobility Support in IPv6".

[7] IETF RFC 768: "User Datagram Protocol".

[8] IETF RFC 793: "Transmission Control Protocol".

[9] IETF RFC 3963: "Network Mobility (NEMO) Basic Support Protocol".

[10] IETF RFC 5213: "Proxy Mobile IPv6".
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2.2 Informative references

The following referenced documents are not essential to the use of the present document but they assist the user with

regard to a particular subject area. For non-specific references, the latest version of the referenced document (including

any amendments) applies.

[i.1] COMeSafety Deliverable 3.1 - Version 2.0 - March 2009: "European ITS CommunicationArchitecture - Overall Framework - Proof of Concept Implementation.

[i.2] PRE-DRIVE C2X Deliverable 1.4 - Version 1.2 - August 2009: "Refined Architecture". .

[i.3] GeoNet Deliverable 1.1 - Version 1.0 - March 2009: "Preliminary Architecture Design".

[i.4] ITU-R Recommendation M.687-2: "International Mobile Telecommunications 2000 (IMT-2000)".

[i.5] IETF RFC 3753: "Mobility Related Terminology".

[i.6] 3GPP: "UMTS Standard, Release 08 Specification".

NOTE: Available at:http://www.3gpp.org.

[i.7] IETF RFC 4213: "Basic Transition Mechanisms for IPv6 Hosts and Routers".

[i.8] IETF RFC 2185: "Routing Aspects of IPv6 Transition".

[i.9] ETSI TS 102 637-1: "Intelligent Transport Systems (ITS); Vehicular Communications; Basic Set

of Applications; Part 1: Functional Requirements".


of Applications; Part 2: Specification of Co-operative Awareness Basic Service".


of Application; Part 3: Specification of Decentralized Environmental Notification Basic Service".

[i.12] ETSI ES 202 663: "Intelligent Transport Systems (ITS); European profile standard for the physical

and medium access control layer of Intelligent Transport Systems operating in the 5 GHz

frequency band".

[i.13] ETSI TS 102 636-1: "Intelligent Transport Systems (ITS); Vehicular Communications;

GeoNetworking; Part 1: Requirements".

[i.14] ETSI TS 102 731: "Intelligent Transportation Systems (ITS); Security; Security Services and

Architecture".

[i.15] ETSI TS 102 723 (all parts): "Intelligent Transport Systems; OSI cross-layer topics".

[i.16] ETSI TS 102 636-5: "Intelligent Transport Systems (ITS); Vehicular Communications;

GeoNetworking; Part 5: Transport Protocols".

[i.17] ETSI TS 102 636-4-1: "Intelligent Transportation System (ITS); Vehicular communications;GeoNetworking; Part 4: Geographical addressing and forwarding for point-to-point and point-to-

multipoint communications; Subpart 1: Media independent functionalities".

3 Definitions and abbreviations

3.1 Definitions

For the purposes of the present document, the terms and definitions given in [1] and [2] and the following apply:

access router: IPv6 router that provides access to other networks, such as to the ITS access network

NOTE: The definition is taken from [i.5] and adapted to the ITS network architecture.
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access network gateway: router at the edge of a network that connects an ITS station-internal network to the ITS

access network, the public access network, and the private access network

ad hoc network: wireless networks based on self-organization without the need for a coordinating infrastructure

application unit: physical unit in an ITS station that executes applications and uses the communication services of a

communication & control unit (CCU)

communication & control unit:physical communication unit located in an ITS station that implementscommunication protocols and provides communication services

GeoNetworking: network service that utilizes geographical positions and provides ad hoc communication without the

need for a coordinating communication infrastructure

GeoNetworking protocol: network protocol that provides the GeoNetworking service

legacy roadside infrastructure:road infrastructure, e.g. road sensors, loops, networks, switches, router, processing

entities, etc.

legacy services: legacy Internet services, such as WWW, email, Internet access, file transfer, etc.

ITS access network:communication network that interconnects roadside ITS stations among each other in an ITSspecific way and optionally interconnects them to the core network (e.g., the Internet)

ITS ad hoc network:network of the ITS architecture that enables self-organized communication among ITS stations

without the need for a coordinating communication infrastructure

ITS operational support service: service for operation of the ITS, such as the provision of security credentials to

users/ vehicle drivers

ITS station internal network:network that interconnects the different components of an ITS station

mobile network:entire network, moving as a unit, which dynamically changes its point of attachment to the Internet

and thus its reachability in the topology

mobile router:IPv6 router that acts as getway between a IPv6 mobile network and another IP-based network, andcapable of changing its point of attachment to the network, moving from one link to another link

private access network:network that provides data services to a closed user group for a secured access to another

system

proprietary local network: communication network attached to an ITS station, for example a controller area

network (CAN) in a vehicle or a network of roadside legacy infrastructure

public access network:network that provides access to general purpose networks that are publicly accessible

3.2 Abbreviations

For the purposes of the present document, the abbreviations given in [1] and [2] and the following apply:

AU Application Unit

CAN Controller Area Network

CCU Communication and Control Unit

DCC Decentralized Congestion Control

GPRS General Packet Radio Service

IMT International Mobile TelecommunicationsIP Internet Protocol

NEMO Network Mobility

PDCP Packet Data Convergence Protocol

TCP Transmission Control Protocol

TIC Transmit Interval Control

TPC Transmit Power ControlUDP User Datagram Protocol

UE User Equipment


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UMTS Universal Mobile Telecommunication System

WIMAX Worldwide Interoperability for Microwave Access

WWW World Wide Web

4 Network architecture for ITS stationsThe network architecture comprises external and internal networks. External networks interconnect ITS stations among

each other or connect ITS stations to other instances. The following external networks are identified:

ITS ad hoc network.

Access network (ITS access network, public access network, private access network).

Core network (e.g. the Internet).

Additionally, an ITS station can have an internal network that interconnects the components of the ITS station.

The different networks shall provide support for various use cases of road safety, traffic efficiency, infotainment and

business applications. However, it is presumed that the communication within a single network does not meet all therequirements of all applications and use cases. Instead combinations of networks are envisioned, in which multiple ITS

access and networking technologies are applied.

Figure 1: External networks involved in the ITS architecture and their interconnections

Figure 1 represents the highest level of abstraction of the ITS network architecture, where the external networks,

represented by clouds are connected. The networks can be categorized into an ITS domain and a generic domain asspecified in [1]. The external networks can be described as follows:

TheITSad hoc network enables ad hoc communication among vehicle, roadside and personal ITS stations. The

communication is based on wireless technologies, that typically provide a limited communication range (referred to as

'short-range wireless technology') and allow for mobility of the ITS stations forming arbitrary network topologies

without the need for a coordinating communication infrastructure. An example of anITS ad hoc networkis a network ofvehicle, roadside and personal ITS stations interconnected by ITS-G5 [10] wireless technology.

Generally, an access networkenables ITS stations to access networks.


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AnITS access networkis a dedicated network that provides access to specific ITS services and applications and can be

operated by a road operator or other operators. The ITS access network also interconnects roadside ITS stations and

provides communication in between these as well as among vehicle ITS stations via the roadside ITS stations that are

interconnected in theITS access network. This local network can then enable the vehicle ITS stations to communicate

via a roadside infrastructure communication network instead directly in ad hoc mode. As an example, an ITS access

network can connect roadside ITS stations along a highway with a central ITS station (e.g. a road traffic management

centre). In the case that short-range wireless technology is used for communication via roadside ITS stations, theconnectivity to theITS access networkis typically provided intermittently.

Apublic access networkprovides access to general purpose networks that are publicly accessible. An example is an

IMT-2000 [i.4] network that connects vehicle ITS stations to the Internet and provides mobile Internet access.

Aprivate access network,in contrast to a public access network, provides data services to a closed user group for a

secured access to another network. For example, aprivate access networkcan connect vehicle ITS stations to a

company's intranet.

The access networks and the core network provide access to various services:

legacy services , such as WWW, email and many others;

ITS services provided by road traffic management centres and backend services;

ITS operational support services required to operate the ITS, such as security services.

Core component of the architecture is the ITS station, which has two main roles: In its first role, the ITS station is a

network node and acts as a communication source or sink. Likewise an ITS station can be a forwarder of data, e.g. in

theITS ad hoc network. In its second role, the ITS station is placed at the network edge and connect the different

networks via anITS station internal network (see Figure 1).

ITS stations shall be able to communicate via at least one of the following means (see Figure 2):

a) via an ITS ad hoc network;

b) via an ITS access network;

c) via a public access network;

d) via a private access network;

e) via one of the access networks into the core network (e.g. the Internet).

In addition to the networks listed above, an ITS station can also be attached toproprietary local networksof e.g. vehicle

ITS sub-systems and roadside ITS sub-system as presented in [1]. Typical examples are:

Controller Area Network (CAN) in a vehicle ITS sub-system.

Legacy roadside infrastructure in a roadside ITS sub-system.

However, these proprietary networks are outside the scope of the present document.


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Figure 2: High-level network architecture

5 Deployment scenarios of the generic networkarchitecture

The ITS network architecture can be deployed in different scenarios to adapt to specific economical and regulatoryconditions and to facilitate a gradual introduction of ITS. Basically, a deployment scenario is a subset of the overall

architecture (see Figure 2) created by a combination of the different network types.

Four basic deployment scenarios can be defined. The basic deployment scenarios can further be extended to hybridscenarios that combine two or more deployment scenarios. These combinations also include scenarios in which a

network is connected to more than a single network simultaneously.

Scenario A establishes an ITS ad hoc network, which can be connected via an ITS access network to the core network

(e.g. the Internet) (see Figure 3). Deployment scenario B represents an ITS access network, which can be connected to

the core network (e.g. the Internet) (see Figure 4). Deployment scenario C is based on a public access network, which

can also provide connectivity to the core network (e.g. the Internet) (see Figure 5). Deployment scenario D uses a

private access network to connect to other networks or the core network (e.g. the Internet)(see Figure 6).

Figure 3: Deployment scenario A: Ad hoc-centric

In Figure 4, the ITS access network connects roadside ITS stations to each other and provides connectivity to a core

network (e.g. the Internet). Optionally, the ITS access network can also be replaced by a public or private access

network.


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Figure 4: Deployment scenario B: ITS access network-centric

Figure 5: Deployment scenario C: Public access network-centric

Figure 6: Deployment scenario D: Private access network-centric

6 Components of the network architecture

6.1 General

Main component of the network architecture is the ITS station as specified in [1] with the following sub-systems:

vehicle ITS station;

personal ITS station;

roadside ITS station;

central ITS station.

In addition to these instantations, the ITS-S Border Router [1] interconnects networks in the ITS domain with networksin the generic domain. Additionally to the ITS station component, the present document introduces specific network

components related to IPv6 communication [i.5], i.e.:

ad hoc router;

mobile router;

access router; and

access network gateway;

that will be defined below.


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6.2 Sub-components of vehicle ITS stations and roadside ITSstations

Vehicle ITS stations and roadside ITS stations consist of two types of sub-components, the Communication & Control

Unit (CCU)and theApplication Unit (AU) (Figure 7). In general, a CCU executes a communication protocol stack. An

AU runs a single or a set of applications and utilizes the CCU's communication capabilities.

In a possible implementation, the CCU executes the ITS access technology, ITS network & transport, and the ITS

facilities layers, whereas the ITS application layer resides in the AU. The distinction between AU and OBU is logical;

all layers can also be implemented in a single physical unit.

NOTE: The components of a personal ITS station and central ITS station will be refined at a later stage of the

network architecture definition.

The CCU shall be equipped with at least a single ITS external communication interface to provide connectivity to the

ITS ad hoc networkor the different access networks (ITS access network, public access network, private access

network). The CCU and the AU can be equipped with one or multiple ITS internal communication interfaces.

Moreover, an AU can have an external communication interface ('Gateway Interface' in Figure 7) for access to the

proprietary local network.

The ITS internal communication interface shall connect AUs with CCUs, AUs with other AUs, and CCUs with other

CCUs via the ITS station-internal network. AUs and CCUs can form a mobile network [i.5], where the AUs obtainconnectivity to the networks via the external communication interface of the CCU. AU and CCU can reside in a single

physical unit.

Figure 7: Sub-components of a vehicle ITS station and a roadside ITS station

The CCU can be further sub-divided into logical network components of different types operating at the network layer:

ad hoc router;

mobile router;

access router; and

access network gateway;

that are responsible for routing and forwarding of packets in the corresponding networks.

An ad hoc routershall be associated with the ITS ad hoc networkand executes an ad hoc networking protocol, such as

the GeoNetworking protocol.

A mobile router is a network component of the vehicle ITS station and shall provide IP connectivity of the ITS station

internal network to an access router. The mobile router is capable of changing its point-of-attachment to the access

network.


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The access router[i.5] is a specific ITS-S router [1] based on IP. It offers IP connectivity to ITS stations and acts as a

default router to the ITS stations it is currently serving. The access router is part of an access network, such as theITS

access network.

An access network gateway[i.5] is a specific ITS-S border router [1] based on IP. It connects:

an ITS internal network and an access network;

an access network and the core network.

6.3 Network connectivity among ITS stations

The following figures 8 to 11 show the connectivity among the ITS stations, where the link between the ITS stationsrepresents an abstraction of the respective networks. The ITS stations are interconnected to ITS stations of different

type (e.g. the vehicle ITS station and the roadside ITS station in Figure 8), but also to ITS stations of the same type

(e.g. vehicle ITS stations among each other as in Figure 8).

In the figures below, the ITS-S border router [1] connects access networks with the core network (e.g. the Internet),

i.e. the ITS access network (Figure 8) and Figure 9, the public access network (Figure 10) and the private access

network (Figure 11). For IP-based networks, the ITS-S border router is an access network gateway [i.5].

Figure 8: Connectivity among ITS stations for deployment scenario A

Figure 9: Connectivity among ITS stations for deployment scenario B


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Figure 10: Connectivity among ITS stations for deployment scenario C

Figure 11: Connectivity among ITS stations for deployment scenario D

6.4 Network reference points

The following network reference points are defined (Figure 8 to Figure 11):

RA Reference point between vehicle ITS stations via the ITS ad hoc network.

RB Reference point between vehicle ITS station and roadside ITS station via the ad hoc network.

RC Reference point between personal ITS stations via the ITS ad hoc network.

RD Reference point between personal ITS station and roadside ITS station via the ad hoc network.

RE Reference point between vehicle ITS station and personal ITS station via the ITS ad hoc network.

RF Reference point between roadside ITS stations via the ITS access network.

RG Reference point between roadside ITS station and ITS-S Border Router via the ITS access network.

RH Reference point between central ITS station and ITS-S Border Router via the core network (e.g. the

Internet).


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RI Reference point between vehicle ITS station and roadside ITS station via the ITS access network.

RJ Reference point between personal ITS station and roadside ITS station via the ITS access network.

RK Reference point between vehicle ITS station and roadside ITS station via the public access network.

RL Reference point between vehicle ITS station and central ITS station via the public access network.

RM Reference point between personal ITS station and roadside ITS station via the public access network.

RN Reference point between personal ITS station and central ITS station via the public access network.

RO Reference point between vehicle ITS station and personal ITS station via the public access network.

RP Reference point between roadside ITS station and central ITS station via the public access network.

RQ Reference point between roadside ITS station and ITS-S Border Router via the public access network.

RR

Reference point between roadside ITS station and central ITS station via the private access network.

RS Reference point between roadside ITS station and ITS-S Border Router via the private access

network.

7 ITS station protocol architecture

7.1 Protocol stack overview

The protocol stack of an ITS station (Figure 12) specified in [1] basically follows the ISO/OSI reference model [2] and

defines four horizontal protocol layers and two vertical protocol entities. This clause gives an overview of the protocolstack and focuses on networking aspects. The horizontal protocol layers are:

ITS access technologieslayer covers various communication media and related protocols for the physical anddata link layers. The access technologies are not restricted to specific type of media, though most of the access

technologies are based on wireless communication. The access technologies are used for communication

inside of an ITS station (among its internal components) and for external communication (for example with

other ITS stations). For external communication, some of the ITS access technologies represent complete,non-ITS specific communication systems (such as GPRS, UMTS, WiMAX) that are regarded as 'logical links'

over which ITS data is transparently transported.

The ITS network & transport layer comprises protocols for data delivery among ITS stations and from ITSstations to other network nodes, such as network nodes in the core network (e.g. the Internet). ITS network

protocols particularly include the routing of data from source to destination through intermediate nodes and theefficient dissemination of data in geographical areas. ITS transport protocols provide the end-to-end delivery

of data and, depending on requirements of ITS facilities and applications, additional services, such as reliable

data transfer, flow control and congestion avoidance. A particular protocol in the ITS network & transport

layer is the Internet protocol IP version 6 (IPv6). The usage of IPv6 includes the transmission of IPv6 packets

over ITS network protocols, dynamic selection of ITS access technologies and handover between them, as

well as interoperability issues of IPv6 and IPv4.

The ITS facilities layer provides a collection of functions to support ITS applications. The facilities providedata structures to store, aggregate and maintain data of different type and source (such as from vehicle sensors

and from data received by means of communication). As for communication, ITS facilities enable various

types of addressing to applications, provide ITS-specific message handling and support establishment and

maintenance of communication sessions. An important facility is the management of services, including

discovery and download of services as software modules and their management in the ITS station.

The ITS applications layer refers to ITS applications and use cases for road safety, traffic efficiency,infotainment and business.


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Figure 12: Reference protocol stack of an ITS station

The two vertical protocol entities are:

ITS managemententity is responsible for configuration of an ITS station, cross-layer information exchangeamong the different layers and others tasks.

ITS securityentity provides security and privacy services, including secure messages at different layers of thecommunication stack, management of identities and security credentials, and aspects for secure platforms(firewalls, security gateway, tamper-proof hardware).

NOTE: Figure 12 shows a simplified version of the ITS station reference architecture specified in [1].

7.2 Protocols of the ITS network & transport layer

The ITS network & transport layer comprises several network and transport protocols (Figure 13). In detail an ITS

station can execute the following protocols at the ITS network & transport layer:

GeoNetworkingprotocol. For usage of the GeoNetworking over different ITS access technologies, thespecification of the protocol is split into a media-independent part and a media-dependent part (potentially

multiple parts), such as for ITS-G5 [10].

Transport protocolsover GeoNetworking, such as the Basic Transport Protocol and other GeoNetworkingtransport protocols as they may be defined later.

Internet protocol IP version 6[5] with IP mobility support [6] and optionally support for network mobility(NEMO) [5]or other approaches depending on the deployment scenario.

Internet protocol IP version 4for transition to IPv6 [4].

User Datagram Protocol UDP [5].

Transmission Control Protocols TCP [6].

Other network protocols.

Other transport protocols,such as SCTP.

Figure 13: Details of the ITS network & transport layer


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The network and transport protocols can operate over various ITS access technologies as specified in [1]. For specific

ITS access technologies, however, the usage of network and transport protocols can be restricted. For example, for

ITS-G5 [10] the GeoNetworking protocol shall be the only network protocol that is used directly on the top of ITS-G5.

7.3 Assembly of network and transport protocols in the ITS

station protocol stack

7.3.1 Overview

For protocol stacks involving the GeoNetworking protocol and IPv6, protocols shall be assembled in one of the

following ways described in clauses 7.3.2, 7.3.3 and 7.3.4. The protocol stacks for other network protocols are

described in clause 7.3.5.

For the GeoNetworking protocol, the underlying ITS access technologies are limited to short-range wireless

technologies, such as ITS-G5 [10].

7.3.2 GeoNetworking protocol stackThe GeoNetworking protocol stack may be assembled with the GeoNetworking protocol and ITS-specific transport

protocols as envisaged in TS 102 636-5 [i.16] at the top of the GeoNetwork protocol as depicted in Figure 14.

Figure 14: GeoNetworking protocol stack in an ITS station

7.3.3 IPv6 stack

The IPv6 stack may be assembled with the IPv6 protocol and related transport protocols UDP [7], TCP [8] and others as

depicted in Figure 15.

Figure 15: IPv6 stack in an ITS station


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7.3.4 Combination of the GeoNetworking protocol and IPv6

This protocol stack combines the stacks in clauses 7.3.2 and 7.3.3. In this protocol stack (Figure 16), IP shall run at thetop of the GeoNetworking protocol or directly at the top of the ITS access technologies.

Figure 16: Combined GeoNetworking and IPv6 stack in an ITS station

7.3.5 Protocol stacks for other network protocols

Further protocol stacks can be defined for other network protocols.

In order to meet application and system requirements, the usage of other network protocols in parallel to the protocol

stacks defined in clauses 7.3.2, 7.3.3 and 7.3.4 can be restricted. For example, other network protocols must not be used

at the top of ITS-G5 [10] operating in the ITS-G5A frequency band.

8 Interfaces and service access points

The ITS network & transport layer shall provide services to the ITS Facility layer. In order to provide its service, the

ITS network & transport layer shall use services from other layers and entities, namely the ITS access technology layer,

ITS management entity and ITS security entity. In an ITS station, the following four interfaces are defined that are

relevant for the ITS network & transport layer (Figure 17):

INF Interface between the ITS network & transport layer and the ITS facility layer.

IIN Interface between the ITS access technology layer and the ITS network & transport layer.

IMN Interface between the ITS management entity and the ITS network & transport layer.

ISN Interface between the ITS security entity and the ITS network & transport layer.


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Figure 17: Interfaces of the ITS station relevant for the ITS network & transport layer

The services of the protocols shall be made available through service access points (SAPs) as will be specified in the

respective parts of [i.15]. The ITS network & transport layer shall support at least one of the following SAPs for INF

(Figure 18):

SAPGeoAwareSAP for protocols of the ITS facility layer that can utilize the capabilities of the GeoNetworking

protocol, such as addressing geographical areas and are not based on IP. Examples for suchprotocols of the ITS facility layer are described in [i.9], [i.10], [i.11], such as the Cooperative

Awareness Message (CAM)protocol [i.10] and theDecentralized Environmental Message (DEM)

protocol [i.11].

SAPUDP SAP for Internet-based ITS applications and facilities that utilize UDP [7].

SAPTCP SAP for Internet-based ITS applications and facilities that utilize TCP [8].

NOTE 1: SAPs for other transport protocols, such as SCTP may be defined if needed.

Figure 18: SAPs offered by the ITS network & transport layer

In addition, the ITS network & transport layer can support a SAP inside the ITS network & transport layer (Figure 18),

offered by the GeoNetworking protocol to IPv6:

SAPGeoIP SAP for IPv6 packet transport over GeoNetworking (TS 102 636-4-1 [i.17]).


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The GeoNetworking protocol shall use the following SAPs defined by other ITS protocol layers (Figure 19):

Via IMN

SAPGeoConfig SAP for configuration of GeoNetworking.

SAPGeoXlayer SAP for cross-layer information exchange.

NOTE 2: These SAPs are not defined in the ITS management layer (yet).

Via ISN

SAPGeoSec SAP between the GeoNetworking and the corresponding security layer.

NOTE 3: These SAPs are not defined in the ITS security layer (yet).

Via IAN

SAP8022 SAP offered by access technologies based on 802.2 LLC/SNAP. The SAP is

specified in the IEEE 802.2 standard [3].

SAPUMTS SAP between the IPv6 layer and UMTS UE (PDCP) as defined in 3GPP [i.6].

NOTE 4: The SAPs to the ITS access technologies are technology-specific (or at least specific to groups of

technologies, such as 802-type technologies).

NOTE 5: SAPs offered by other ITS access technologies need to be defined in the future.

Figure 19: SAPs used by the ITS network & transport layer

9 Frameworks for network and transport protocols

This clause defines high-level logical functions to be considered in the design of ITS network and transport protocols.


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9.1 GeoNetworking

9.1.1 Ad hoc networking

GeoNetworking shall provide ad hoc networking based on geographical addressing and geographical routing between

ITS stations using short-range wireless technology. It shall allow the addressing of ITS stations based on theirindividual network addresses and also facilitate the addressing of geographical areas. For routing, GeoNetworking shall

support point-to-point and point-to-multipoint communication, as well as the distribution of data packets in

geographical areas, i.e. to all nodes in a geographical area (GeoBroadcast) or to any node in a geographical area

(GeoAnycast).

9.1.2 Addressing

For packet transport, the network elements of ITS stations shall be addressed by network addresses. The address type is

protocol-specific and shall include at least GeoNetworking addresses, IPv6 addresses and IPv4 addresses.

GeoNetworking shall apply a particular concept of geographical addressing, i.e. it shall allow for communication withan ITS station by its network address and geographical position in the ad hoc network. Likewise, it shall also be able to

address ITS stations in geographical areas. IP addresses shall be assigned to an ITS station based on existing approaches

(e.g. by auto-configuration depending on the network scenario). An ITS station can have assigned multiple IP addresses

in order to cope with IP mobility issues. Network addresses of ITS stations can change to alleviate privacy issues.

NOTE: The concept of changing pseudonyms is being defined by TC ITS WG5.

9.1.3 Resource management and data congestion control

ITS applications, in particular safety-related applications, have high requirements on the reliability and the delay of the

data transmission. Considering the limitations of the ITS-related frequency bands, the data load on the wireless channels

can exceed the available network resources and capacity in some situations. Distributed congestion control (DCC) shall

avoid a congestion collapse of the network and shall ensure network stability, throughput efficiency and fair resource

allocation to ITS stations. DCC requires mechanisms on all layers of the protocol stack and a harmonization of these

mechanisms among the layers. The GeoNetwork protocol shall utilize DCC by the combination of differentmechanisms, namely transmit power control (TPC) and transmit interval control (TIC). These mechanisms shall utilize

support from lower layers for per-packet control of radio parameters as well as requirements from upper layers.

9.1.4 Integration of GeoNetworking and IPv6

The ITS ad hoc network shall provide the transport of IPv6 packets enhanced by GeoNetworking for communicationamong ITS stations. The delivery of IPv6 packets shall be achieved byIPv6 in GeoNetworking header tunnelling,

i.e.encapsulation of IPv6 packets (header and payload) into GeoNetworking packet headers and routing of the

encapsulated packets by the GeoNetworking protocol. From the IPv6 layer perspective, the ITS stations should appear

as attached to the same IPv6 'link'. For different communication scenarios, such for ad hoc networking among ITS

stations without connectivity to a communication infrastructure or for communication with IPv6 nodes in the Internet,

when access to the communication infrastructure is available, specific mechanisms for IPv6 address configuration shall

be applied.

When vehicle ITS stations have access to a communication infrastructure, IPv6 support over GeoNetworking should be

enhanced with solutions for IP mobility support. Those solutions achieve global reachability of IP nodes and IP session

continuity. Different approaches for IP mobility can be applied, such as RFC 3775 [6] and RFC 5213 [10]. As an ITS

station can include a set of attached devices (AUs) and form an IPv6 mobile network opposed to a single 'IPv6 node',

NEMO Basic Support [9] should be applied to maintain ongoing sessions during IP handovers.

9.1.5 Backward compatibility to IPv4

In principle, the communication using the Internet protocol in ITS is based on IP version 6. Backward compatibility

from IPv6 to IPv4 is needed as required for legacy Internet applications that require IPv4, and Public Access Networks

that are capable of IPv4 only. In order to achieve the backward compatibility, standard mechanisms should be applied,such as the usage of IP4/IPv6 capable addresses and IPv4 in IPv6 tunnels, or dual-stack IP (see RFC 4213 [i.7] and

RFC 2185 [i.8]).


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9.1.6 Usage of multiple ITS access technologies

GeoNetworking shall be capable for routing of packets over different types of short-range wireless technologies. In casean ITS station is equipped with multiple communication interfaces of different technologies, the GeoNetworking shall

provide mechanisms to choose the communication interface based on policies.

9.1.7 Security and privacy protection

In order to provide secure communication, including authentication, authorization, integrity and non-repudiation, the

GeoNetworking protocol shall support cryptographic protection based on digital signatures and certificates.

Additionally, the networking operations shall be protected by plausibility checks, rate limitation and trustworthiness

assessment. Furthermore, the anonymity of users shall be protected by usage of anonymous identifiers by means of

pseudonyms and anonymous certificates.

More details are described in [i.14] and [i.2].

9.2 Other protocol stacks

NOTE: This will be provided in a future version of the present document if appropriate.


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History

Document history

V1.1.1 March 2010 Publication

Documents

Intelligent Transport Systems (ITS); Cooperative ITS (C-ITS); Release 1 Vehicular Communications - GeoNetworking - Part 3 Network Architecture